<style>
  .change-1 .item1 {
    display: grid;
  }
  .change-1 .item2 {
    position: absolute;
  }
  .change-1 .item3 {
    width: 100%;
  }
  .change-1 .item4 {
    width: 50%;
  }
  .change-2 .item1 {
    position: absolute;
  }
  .change-2 .item2 {
    position: relative; 
  }
  .change-3 .item2 {
    display: flex;
  }
  .change-3 .item3 {
    display: grid;
  }
</style>
<div class="container">
  <div class="item item1"></div>
  <div class="item item2"></div>
  <div class="item item3"></div>
  <div class="item item4"></div>
</div>
